Lake Hitchcock was a
glacial lake that formed approximately 15,000 years ago in the late
Pleistocene epoch. After the
Laurentide ice sheet retreated, glacial ice melt accumulated at the terminal
moraine and blocked up the
Connecticut River, creating the long, narrow lake. The lake existed for approximately 3,000 years, after which a combination of
erosion and continuing geological changes likely caused it to drain. At its longest, Lake Hitchcock stretched from the moraine dam at present-day
Rocky Hill, Connecticut, to
St. Johnsbury, Vermont (about ). Although the
rift valley through which the river flows above Rocky Hill actually continues south to
New Haven, on
Long Island Sound, the obstructing moraine at Rocky Hill diverted the river southeast to its present mouth at
Old Saybrook.
Lake Hitchcock is an important part of the
geology of Connecticut. It experienced annual layering of sediments, or
varves: silt and sand in the summertime (due to glacial meltwater) and clay in the wintertime (as the lake froze). These
varved lake deposits were later used by European settlers for brick-making. The lake was named after
Edward Hitchcock, a geologist from
Amherst College who had studied it.
See also
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